Individuals raised in low socioeconomic (SES) households have been found to bear 20%-40% increased risk of costly chronic and infectious diseases and all-cause mortality, even after accounting for adulthood SES. Illuminating the biological mechanisms of these health risks, recent research has determined that severe and chronic stress endured early in life can embed a decades-long biological residue within the immune system, as reflected in leukocyte basal gene expression profiles, leukocyte telomere length, and levels of chronic inflammation indexed by C-reactive protein. These biological risk factors are further exacerbated by behavioral proclivities, namely, impulsivity (indexed by delay discounting) and mistrust, which are also more probable among those reared in low SES households. The overarching goal of the proposed research is to investigate whether and how this identified biological residue can be reversed in midlife. An innovative upward spiral theory o lifestyle change positions warm and empathic emotional states as key pathways to unlocking the body's inherent plasticity to reverse entrenched biological risk factors. The PI's team has identified an affective intervention - the ancient practice of loving-kindness meditation (LKM) - that produces salubrious biological effects in healthy midlife adults. The innovation of the present study lies in testing this affective intervention in a sample of midlife adults on poor health trajectories by virtue of having low childhood SES plus present-day pathogenic behavioral tendencies (i.e., impulsivity and mistrust). A dual-blind placebo-controlled randomized controlled trial (RCT) is designed to provide proof of principle that early-established biological risks factors are mutable, not permanent. It targets three Specific Aims: (1) To test whether LKM, through its effects on positive emotions, can reverse the biological residue of low childhood SES as reflected in (a) leukocyte basal gene expression (up-regulation of pro-inflammatory genes and down-regulation of antiviral and antibody genes), (b) leukocyte telomere length, and (c) C-reactive protein; (2) to identify plausible behavioral and biological moderators of the hypothesized benefits of LKM in this at-risk sample, with candidate moderators being (a) time spent meditating and (b) metabolic profile; and (3) to identify plausible biological, behavioral, and psychological mediators of the hypothesized biological benefits of LKM-induced positive emotions in this at-risk sample, with candidate mediators being improvements in (a) cardiac vagal tone, (b) delay discounting, and (c) mistrust. This research stands to identify evidence-based interventions to drastically reduce the disease burden that disproportionately affects Americans raised in low SES households.